Indoor hydroponic and soil-based plant growing systems have become indispensable in the indoor horticultural industry. Each system includes and requires plant nutrient media and containers, climate control, lighting, and hydration. Large plants and those native to high intensity sunlight environments typically require high intensity lights for optimal growing conditions, so sufficient light is a major factor in indoor and greenhouse gardening. Typically, light sources requiring power input of up to 1000 watts are necessary. In most cases a light reflector is used with high power light sources to ensure that all available light is being reflected down onto the plants being grown. While these combinations do a sufficient job of replicating sunlight for the purpose of plant growth, they also produce intense heat, which is detrimental in most cases to the plants they're supporting. For this reason, tight control over temperature in the growing environment is paramount and a cooling system of some kind is necessary to prevent general rise in temperature in the growing environment. Facility-wide cooling systems may be used, but such systems are costly and, if operated to cool plants under the high intensity lights, may result in temperatures below optimum in the areas around plants housed in the same facility but under lower intensity lighting.
Since the intensity of light on any given surface is reduced by the square of the distance from the light source, the closer the light source is to the plants, the more light they are receiving. However, the closer the light source is to the plants, the hotter the plants may get. It is necessary to provide a cooling device of some kind to remove heat from the light source and allow 1) room for more lights within a given growing area without raising overall room temperatures above optimal levels and 2) the lights to be moved closer to the plant canopy to allow maximum light absorption without causing the plants harm with intense heat produced by the high intensity light sources.
It is also desirable to center a light source within a reflective housing to optimize the intensity and consistency of the light pattern beneath the reflective housing.
These lights are also used in the aquarium market with similar challenges.